The issue is your part number is not relevant, what version of software that is installed is... If you don't know you can look in the menus on the front panel. Also worth noting you need the admin password, if you don't have it then you need to get a Mitel authorized vendor to work with support to get it reset. If you factory default the system, you will lose your licensing as well, essentially making it a brick if you don't have the license key.